Useful and desirable chemical products are the optically active .alpha.-phenylglycine compounds. For instance, D-.alpha.-phenylglycine is useful for the preparation of .alpha.-aminobenzyl penicillin, and L-.alpha.-phenylglycine is useful for the preparation of asparagine-L-.alpha.-phenylglycine methyl ester (a sweetening agent).
It is already known that mixtures of these optically active phenylglycine amides and optically active phenylglycines can be obtained by the selective enzymatic hydrolytic conversion of DL phenylglycine amides, as applicant has previously disclosed in his U.S. Pat. No. 3,971,700 (the disclosure of which is incorporated herein by reference). It has also been shown that such a mixture can be separated into its respective optically active components by means of ion-exchange column techniques. However, for industrial practice, where long residence times are involved in the use of ion-exchanger columns, this method is difficult to apply without racemization of the product taking place.